This is useful especially for testing, where you can manually instantiate components

well as a followup we should probably create some docs around that. we have not much about that topic.
my company actually had a lot of stuff where we created a app and then did app.injector.instanceof while this is not bad, it's way way way way slower than doing new Controller(dependency1, dependency2) ... and manually constructing the dependency chain. (In some cases it's not just seconds, more like minutes..)
Actually google also has Dagger DI where they encourage that pattern.
However it has one bad thing, you can't test the routing. If you don't rely on the reverse router that might be a problem but there is a pattern to just create Controllers that you can fake and then test all routes at once.

@schmitch Definitely. We need to work on better docs for testing before the next release. Especially given that we are removing a few more global things (mainly action builders).